Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030870AbcCQNzk (ORCPT ); Thu, 17 Mar 2016 09:55:40 -0400 Received: from mail-pf0-f174.google.com ([209.85.192.174]:32768 "EHLO mail-pf0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030843AbcCQNzh (ORCPT ); Thu, 17 Mar 2016 09:55:37 -0400 Subject: Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable To: Juri Lelli References: <1457932932-28444-1-git-send-email-mturquette+renesas@baylibre.com> <1457932932-28444-5-git-send-email-mturquette+renesas@baylibre.com> <20160315212047.GE6344@twins.programming.kicks-ass.net> <20160315214043.30639.75507@quark.deferred.io> <20160315214821.GM6344@twins.programming.kicks-ass.net> <20160315223701.30639.43127@quark.deferred.io> <56E8D4D9.1060202@linaro.org> <20160316080503.GS6344@twins.programming.kicks-ass.net> <20160316100257.GC18212@e106622-lin> <56E99E25.9070002@linaro.org> <20160317094046.GF18212@e106622-lin> Cc: Peter Zijlstra , Michael Turquette , rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, morten.rasmussen@arm.com, dietmar.eggemann@arm.com, vincent.guittot@linaro.org, Michael Turquette , Patrick Bellasi From: Steve Muckle X-Enigmail-Draft-Status: N1110 Message-ID: <56EAB756.1050805@linaro.org> Date: Thu, 17 Mar 2016 06:55:34 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <20160317094046.GF18212@e106622-lin> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 745 Lines: 15 On 03/17/2016 02:40 AM, Juri Lelli wrote: >> Could the default schedtune value not serve as the out of the box margin? >> > I'm not sure I understand you here. For me schedtune should be disabled > by default, so I'd say that it doesn't introduce any additional margin > by default. But we still need a margin to make the governor work without > schedtune in the mix. Why not have schedtune be enabled always, and use it to add the margin? It seems like it'd simplify things. I haven't looked at the schedtune code at all so I don't know whether this makes sense given its current implementation. But conceptually I don't know why we'd need or want one margin in schedutil which will be tunable, and then another mechanism for tuning as well.